1. Field of the Invention
The present invention relates to a shift register of a liquid crystal display device, and more particularly, to a shift register having a structure capable of utilizing the non-display region of a liquid crystal panel efficiently.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) device is adapted to display an image by adjusting light transmittance of a liquid crystal using an electric field. The LCD device includes a liquid crystal panel having pixel areas arranged in matrix form and a driving circuit for driving the liquid crystal panel. The driving circuit includes a gate driver for driving gate lines, a data driver for driving data lines, a timing controller for supplying control signals for control of the gate driver and data driver, and a power supply for supplying various drive voltages to be used in the LCD device.
In particular, the gate driver includes a shift register for sequentially outputting scan pulses, which will hereinafter be described in detail with reference to FIG. 1. FIG. 1 schematically shows the configuration of a conventional shift register. As shown in FIG. 1, a conventional shift register has n stages 101 to 10n connected in cascade. The stages 101 to 10n sequentially output output pulses Vout1 to Voutn in response to a clock pulse CLK supplied thereto. These output pulses Vout1 to Voutn are sequentially supplied to the gate lines of the liquid crystal panel to drive the gate lines accordingly.
To increase the screen area of the LCD device, the number and length of the gate lines should also be increased. Furthermore, in order to drive the gate lines at high speed, the area of each switching device in each stage should be increased. Overall, the size of the shift register should be increased to obtain an LCD device with a large screen area operating at a high speed.
The liquid crystal panel has a display region, and a non-display region surrounding the display region. The stages of the shift register are formed in a portion of the non-display region located at one side of the display region of the liquid crystal panel. However, the increase in the switching device area, as mentioned above, makes it difficult to integrate a large number of switching devices in the limited space of the non-display region.